The present invention relates to programmable timers. Timers including a rotating dial which can be manually programmed for specified timer intervals during a 24-hour period are, in general, known. An example is described in U.S. Pat. No. 3,588,396 issued on June 28, 1971 to G. D. Fredell. As described therein, a cylindrical drum is provided with a plurality of spaced channels into which pins can be inserted. Rotation of the drum causes the pins to sequentially engage a mechanism to controllably open and close an electrical switch.
Timers capable of initiating certain events at predetermined times during a day for predetermined intervals on selected days of a week are also known. For example, U.S. Pat. No. 3,864,539 issued on Feb. 4, 1973, to Hansen describes a timer including respective rotating drums or dials corresponding to the time of day and the days of the week. Switch elements mounted on each dial can be moved between engaging and disengaging positions. When in the engaging positions, the switch elements engage microswitches and a controlled device is activated. The controlled device is not activated for any day, however, in which the respective switch element is in its disengaging position. Timing devices of this type permit selection of days in which the controlled device is not activated. Such devices tend to be overly complex, often employing numerous switches to mechanically accomplish the programming of the device, and offer less reliability.